Resistance-box



(No Model.) 2 Sheets-Sheet 1.

A. 0. BENEGKE. RESISTANCE BOX.

No. 511,286. Patented Dec-. 19,1893.

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(No Model.) 2 Sheets-Sheet 2-.

A. 0. B'ENECKE; RESISTANCE 11011.

No. 511,286. Patented Dec. 19, 1893.

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UNITED STATES PATENT OFFIQE.

ADELBERT' BENEOKE, OF NEXVARK, NEW JERSEY.

RESISTANCE-BOX.

SPECIFICATION forming part of Letters Patent No. 511,286, dated December 19, 1893.

Application filed September 10, 1892. Serial No. 445,491. (No model.)

To aZZ whom it may concern.-

Be it known that I, ADELBERT O. BENECKE, of Newark, Essex county, New Jersey, have invented a new and useful Improvement in Bridges or Resistance-Coils, of which the followingis a specification.

The object of my invention is to provide an improved form of bridge or resistance coil for making electrical measurements, in which equal variations in resistance can be obtained by the use of fewer coils than is commonly employed in instruments of this class, and whereby the coils are arranged in more compact form and smaller compass.

In the accompanying drawings, Figure 1 is a well-known electrical diagram representing the W heatstone bridge. Fig. 2 is an electrical diagram showing the arrangement of con nections of my improved bridge or resistance coil. Fig. 3 is a plan view of one set or series of coils together with their respective contact plates. Fig. 4 is a vertical longitudinal section through the apparatus, and Fig. 5 is a plan view showing the various contact plates and also the coil spools in place.

Similar letters and figures of reference indicate like parts.

In the diagram Fig. 1, a and I) represent the arms of the bridge in which are placed the fixed resistances. R is the arm in which is placed the variable resistance and X the arm which includes the unknown quantity to be measured. G is the galvanometer and B the battery indicated by the usual symbols and connected in circuit with the bridge in the ordinary way.

In Fig. 2, similar parts being correspondingly lettered and figured, the connections for purposes of a bridge will be readily understood. Beginning at the contact plate 1, the arm 1) meets the arm a, which extends from the contact plate 2. From the point of junction of the arms a and l) of the bridge, the wire 3 proceeds to the bindingpost-l. The binding post 4. connects with one pole of the battery B, the other pole of this battery connecting with the binding post From the binding post 5 proceeds a wire, 6, in which is placed the contact key 7. This wire connects with a plate A which connects with the series of resistance coils R. Not shown in Fig. 2. The

other end of this series of resistance coils communicates with a plate, 9,which plate, by means of a wire, 10, communicates with the binding post 12. In the wire is a contact key, 11. The galvanometer (l is connected between the binding post 12 and the binding post 13. 1 and 15 are two binding posts to which is connected the unknown resistance, X. The binding post 15 is connected by a wire 16 with the wire 6. The binding post 1t is connected by a wire, 17, with the plate 18, and by wire 19 with the post 13.

Referring now to Figs. at and 5, 20 is the containing box or case provided with a cover, 21. 22 is a platform of ebonite on the under side of which are fastened the contact plates, as A, B, O, &c. The resistance coils shown at 2 3 are made in the usual way, and are supported upon metal shafts or rods, 24., which are tapped into the under sides of the metal plates or blocks. Each coil is supported upon a nut,25, upon the threaded end of the shaft 2 1. The vertical pins or shafts 26 are fairleaders for the wires passing from one coil to another. Connection between the metal plates to cutout the resistance coils as hereinafter will be explained, is effected in the usual way by plugs, one of which is shown at 27. This plug passes down through an opening in the ebonite platform and enters a wedge-shaped aperture between the metal contact plates.

I desire it to be understood that I do not claim herein the construction of a resistance coil or bridge in which the contact plates are arranged on the lower side of the supporting platform. Neither do I claim such an apparatus in which the metal contact plates are wholly inclosed in the box or case so that the parts of the ebonite or rubber platform which supports them are thus protected from the combined influence of the atmosphere and of desired proportions and are used in the ordinary way in which such coils are employed in the commonly known bridge instrument. The first series of resistance coils in the variable resistance is represented at 0 the second series at the third series at 0 and the fourth series .at 0 These seriesmay represent units, tens, hundreds and thousands of ohms respectively. It will be observed that the series 0 is supported on the bar A, that the second series 0 is supported on the bar B, and that between the bar A and the bar B there are five smaller contact plates, 0, D,E, F, H. Beginning at that end of theseries of coils c which is at the bottom of 'the drawings, it will be observed that the first coil has its terminals connected tothe plate B and the plate 0; the second coil has its terminals connected to the plate (Land the plate D; the third coilhas its terminals connected to the plateDandthe .plate E; andso on to the sixthcoil, ..wh.ic h has its terminals connected to the plate Htand theplate vA. Thisarrangement will bebetter understood by reference to Fig. 3, wherethe coils are represented symbolically by spirals, marked one ohm and .fi ve ohms.

.Supposethat each coil .except the last of theserieslwhich connects plate A and plate H tov be ofoneohm resistance, as marked in Fig. 3, and that the coil thus excepted be of five ohm resistance, then with the arrangement shown for plugging in Fig. 3, it will be plain that by the use ofsix coils I can get all the variations in resistancewhich ordinarily require ten coils in the resistance box as it is generally made. ,Toillustrate, supposing the current to' come in atthearrow I of Fig. 3 and togo out at thearrowJ, if I should put a plug in thehole marked zero and thereby connect plate BandplateA, it is plain that the current will pass through .none of thecoils. If I place theplug in the hole marked 1, then thecurrent will ,go through the coil between the plates Band O, which is one ohm;.and similarly, if I successively place theplug in the holes2, 3, 4,5, the current will in each case pass throughone more coil, and thus the resistance may. be. gradually increased from one to five ohms. Now to go to six ohms, I place simply a plug in the hole 6. Then the current, will pass through the plate B to the plate F, and thence throughone ohm resistance to the plate H, and thence through five ohm resistance to the plate A. To obtain seven ohm resistance I placethe plug in a hole, 7; and finally to make ten ohm resistance, all of the holes are left unplugged, and the plug is simply put in a blind hole, which is here marked 10, and whichestablishes no connections, being merely an aperture in the bar B. Of course it is to be understood that this arrangement of contact plates in connection with the series c of coils is repeated with all the other series of coils; and it is in this more especially that the distinctive feature of my invention resides. ,As I have before stated, it allows ofthe saving of forty per. cent. of coils as now. commonly used, with the consequent economy in expense and the insurance of 6 plates, as A, B, 0,-two resistances respectively interposed between plates B and O and G and A, and circuit connectionsand meanswhereby plate 0 may beelectrically connected-with either of saidplatesA or B'.'

, 3. The combinatien ina set ofresistance coils orbridge ota seriesof three fixed-contact plates, as A, B, 0, two resistances respectively interposed between plates B and C(and O and A, andcircuit connectionsand means whereby plate 0 may beelectrically connected with either of said plates A or B, and whereby said plate Aand plate-B may be electrically connected to cut out the said resistances.

4. The combination in a s'et of resistance coils or bridge of a series of three fixed contact plates, as A, B, C, two resistancesrespectively interposed betweenplates B and O andCand A, the resistance. between plates 0 and Abeing greater than the resistance between plates B and G, and circuit connections and means whereby, plate 0 may be electricallyconnected with either of said plat-es A or B.

5. The combination in a set of resistance coilsor bridge of .a series of fixedcontact plates, as B, C, D, E, F, H,A,a series of equal resistances interposed respectively between the plates B, O, 'D, E, F, H, a greater resistance interposed between the plates H A, and circuit connections and means whereby said plates Hand A may be electrically connected tocut out said greater resistance, andwhereby said plates 0, D,'E, F, may be connected with either of saidplates B or A.

6. The combination in a set of resistance coils or bridge of a series of fixedcontact plates,as B, O, D, E, F, H, A, a series of equal resistances interposed respectively between the plates B, O, D, E,F, H, a resistance equal to the sum of the aforesaid equal resistances interposed between the plates H and A, and circuit connections and means whereby said plates H and A may be electrically connected ,to cut out said greater resistance, and whereby said plates 0, D, E, F, may beconnected with either ofsaid plates B or A.

ADELBERT O. BENEOKE.

Witnesses:

' A. H. HOEFER,

JOHN G. YOUNG. 

